Crichton was quoted a number of times on the adage, which he in turn claimed was in more general use. However, he seems to have been key in popularizing it. See here for more discussion and specific citations.

You can never read your own book with the innocent anticipation that comes with that first delicious page of a new book, because you wrote the thing. You’ve been backstage. You’ve seen how the rabbits were smuggled into the hat. Therefore ask a reading friend or two to look at it before you give it to anyone in the publishing business. This friend should not be someone with whom you have a romantic relationship, unless you want to break up.

You don’t always have to go so far as to murder your darlings — those turns of phrase or images of which you felt extra proud when they appeared on the page — but go back and look at them with a very beady eye. Almost always it turns out that they’d be better dead. (Not every little twinge of satisfaction is suspect — it’s the ones which amount to a sort of smug glee you must watch out for.)